(1) bonds or evidences of debt which are secured by first mortgages or deeds of trust on improved unencumbered real property located in the United States;
(2) chattel mortgages in connection therewith pursuant to section 565 of this title;
(3) the equity of the seller of any such property in the contract for a deed, covering the entire balance due on a bona fide sale of such property, in amount not to exceed $10,000 or the amount permissible under section 553 of this title, whichever is greater, in any one such contract for deed, nor in any amount in excess of the following percentages of the actual sale price or fair value of the property, whichever is the smaller:
(A) if a dwelling primarily designed for single family occupancy and occupied by the purchaser under such contract, 75 percent;
(B) in all other cases, 66 ⅔ percent;
(4) purchase money mortgages or like securities received by it upon the sale or exchange of real property acquired pursuant to section 566 of this title;
(5) bonds or notes secured by mortgage or trust deed guaranteed or insured by the Federal Housing Administration under the terms of the Act of Congress of the United States, June 27, 1934, entitled the “National Housing Act,” as amended; and
(6) bonds or notes secured by mortgage or trust deed guaranteed or insured as to principal in whole or in part by the Administrator of Veterans' Affairs pursuant to the provisions of Title III of the Act of Congress of the United States, June 22, 1944, entitled the “Servicemen's Readjustment Act of 1944,” as amended.